Possible roles of intestinal P-glycoprotein and cytochrome P450 3A on the limited oral absorption of irinotecan.

OBJECTIVES: Irinotecan is a widely intravenously used drug for the treatment of certain types of solid tumours. The oral administration of irinotecan has recently been recognized as being a more effective method for the treatment than intravenous administration. However, the limited oral bioavailability of irinotecan poses a problem for its oral delivery. In this study, we report on an investigation of the mechanism responsible for the limited oral absorption of irinotecan using rats as models. METHODS: The intestinal absorption of irinotecan in the absence and presence of several compounds was examined using intestinal loop method. The pharmacokinetics of irinotecan was investigated when verapamil, an inhibitor of the P-glycoprotein (P-gp) and cytochrome P450 3A (CYP3A) was pre-administered. KEY FINDINGS: The intestinal absorption of irinotecan was enhanced in the presence of verapamil, indicating that efflux by intestinal P-gp contributes to its limited oral absorption. Indeed, the oral bioavailability of irinotecan was increased when verapamil was orally pre-administered. This increased oral bioavailability was accompanied by a slight but significant decrease in the formation of a metabolite produced by the action of CYP3A. CONCLUSION: The findings presented herein suggest that intestinal efflux by P-gp is mainly and intestinal metabolism by CYP3A is partially responsible for the limited oral absorption of irinotecan.

Effects of M-1, a Major Metabolite of Sarpogrelate, on 5-HT-Induced Constriction of Isolated Human Internal Thoracic Artery.

Sarpogrelate, a selective 5-hydroxytryptamine (5-HT)2A receptor antagonist, inhibits 5-HT-induced platelet aggregation and vasoconstriction. It improves ischemic symptoms in patients with arteriosclerosis obliterans. M-1 is a major metabolite of sarpogrelate, and has been reported to show a higher affinity for the 5-HT2A receptor on platelets than sarpogrelate. However, the effects of M-1 on 5-HT-induced constrictive response in human blood vessels have not been investigated. The internal thoracic artery (ITA) is the key conduit for coronary artery bypass grafting (CABG). 5-HT has been implicated as playing an important role in the pathogenesis of vasospasm. Thus, in the present study, the effects of M-1 on 5-HT-induced vasoconstriction were examined in isolated human endothelium denuded ITA. M-1 inhibited 5-HT-induced vasoconstriction in a concentration-dependent manner. At the highest concentration, M-1 almost completely inhibited the 5-HT-induced vasoconstriction. Expression of 5-HT2A and 5-HT1B receptor proteins in the membrane fraction of ITA smooth muscle cells was confirmed by Western blot analysis. Individually, supramaximal concentrations of sarpogrelate and SB224289, a selective 5-HT1B receptor antagonist, only partially inhibited the 5-HT-induced vasoconstriction. However, simultaneous pretreatment with both these antagonists almost completely inhibited the 5-HT-induced vasoconstriction. The inhibitory effect of M-1 pretreatment mimicked the inhibitory effect of simultaneous pretreatment with sarpogrelate and SB224289. These results suggest that M-1 has antagonistic effects not only on the 5-HT2A receptor but also on the 5-HT1B receptor in human ITA smooth muscle cells. M-1 may be useful as a lead compound for the development of drugs for the treatment of 5-HT-induced vasospasms in CABG.

Caffeine Has a Synergistic Anticancer Effect with Cisplatin via Inhibiting Fanconi Anemia Group D2 Protein Monoubiquitination in Hepatocellular Carcinoma Cells.

Cisplatin is an anticancer agent and induces DNA interstrand cross-links (ICLs). ICLs activate various signaling processes and induce DNA repair pathways, including the Fanconi anemia (FA) pathway. FA complementation group D2 (FANCD2) is monoubiquitinated in response to DNA damage, leading to activation of the DNA double-strand-break repair protein, RAD51. Caffeine increases the anticancer activity of cisplatin by inhibiting DNA repair; however, details of the mechanism remain unclear. We investigated the mechanism responsible for the synergistic anticancer effect of cisplatin and caffeine in HepG2 human hepatocellular carcinoma cells, focusing on the FA pathway. Caffeine (≥100 µg/mL) significantly enhanced the antiproliferative activity induced by 3.8 µg/mL cisplatin. Caffeine (200 µg/mL) promoted apoptosis and inhibited the increase in the proportion of viable cells in S phase that occurred in the presence of 3.8 µg/mL cisplatin. Both FANCD2 monoubiquitination and RAD51 expression were significantly inhibited by co-treatment with 200 µg/mL caffeine and 3.8 µg/mL cisplatin compared with cisplatin alone. In conclusion, caffeine enhances the anticancer effect of cisplatin by inhibiting FANCD2 monoubiquitination. In HepG2 cells, caffeine might inhibit the FA pathway and thereby regulate DNA damage responses such as DNA repair and apoptosis.

Activation of Cellular Immunity in Herpes Simplex Virus Type 1-Infected Mice by the Oral Administration of Aqueous Extract of Moringa oleifera Lam. Leaves.

Moringa oleifera Lam. is used as a nutritive vegetable and spice. Its ethanol extract has been previously shown to be significantly effective in alleviating herpetic skin lesions in mice. In this study, we evaluated the alleviation by the aqueous extract (AqMOL) and assessed the mode of its anti-herpetic action in a murine cutaneous herpes simplex virus type 1 (HSV-1) infection model. AqMOL (300 mg/kg) was administered orally to HSV-1-infected mice three times daily on days 0 to 5 after infection. AqMOL significantly limited the development of herpetic skin lesions and reduced virus titers in the brain on day 4 without toxicity. Delayed-type hypersensitivity (DTH) reaction to inactivated HSV-1 antigen was significantly stronger in infected mice administered AqMOL and AqMOL augmented interferon (IFN)-γ production by HSV-1 antigen from splenocytes of HSV-1-infected mice at 4 days post-infection. AqMOL administration was effective in elevating the ratio of CD11b(+) and CD49b(+) subpopulations of splenocytes in infected mice. As DTH is a major host defense mechanism for intradermal HSV infection, augmentation of the DTH response by AqMOL may contribute to their efficacies against HSV-1 infection. These results provided an important insights into the mechanism by which AqMOL activates cellular immunity. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of brazilian propolis on exacerbation of respiratory syncytial virus infection in mice exposed to tetrabromobisphenol a, a brominated flame retardant.

Tetrabromobisphenol A (TBBPA), a brominated flame retardant, has been found to exacerbate pneumonia in respiratory syncytial virus- (RSV-) infected mice. We examined the effect of Brazilian propolis (AF-08) on the exacerbation of RSV infection by TBBPA exposure in mice. Mice were fed a powdered diet mixed with 1% TBBPA alone, 0.02% AF-08 alone, or 1% TBBPA and 0.02% AF-08 for four weeks and then intranasally infected with RSV. TBBPA exposure increased the pulmonary virus titer and level of IFN- γ , a representative marker of pneumonia due to RSV infection, in the lungs of infected mice without toxicity. AF-08 was significantly effective in reducing the virus titers and IFN- γ level increased by TBBPA exposure. Also, AF-08 significantly reduced proinflammatory cytokine (TNF- α and IL-6) levels in the lungs of RSV-infected mice with TBBPA exposure, but Th2 cytokine (IL-4 and IL-10) levels were not evidently increased. Neither TBBPA exposure nor AF-08 treatment affected the anti-RSV antibody production in RSV-infected mice. In flow cytometry analysis, AF-08 seemed to be effective in reducing the ratio of pulmonary CD8a(+) cells in RSV-infected mice with TBBPA exposure. TBBPA and AF-08 did not exhibit anti-RSV activity in vitro. Thus, AF-08 probably ameliorated pneumonia exacerbated by TBBPA exposure in RSV-infected mice by limiting excess cellular immune responses.

Effects of oral administration of probiotics from Mongolian dairy products on the Th1 immune response in mice.

We investigated 10 lactic acid bacteria strains with probiotic potential prepared from Mongolian dairy products for their ability to induce T helper type-1 (Th1) cytokine production in mouse immune cells in vitro and in vivo. Among these strains, the Lactobacillus plantarum 06CC2 strain was effective in elevating the level of interleukin (IL)-12p40 in co-culture with J774.1 cells and the levels of IL-12 and interferon (IFN)-γ in co-culture with mouse spleen cells in vitro. Oral administration of this strain augmented the gene expression of IFN-γ and IL-12p40 and enlarged the population of CD4(+), CD25(+), and CD49b(+) cells in the spleens of normal mice. It also significantly elevated the gene expression of IL-12 receptor ß2 as well as IL-12p40 and IFN-γ in Peyer's patches. Thus oral administration of strain 06CC2 was effective in inducing Th1 cytokine production activating the Th1 immune response associated with intestinal immunity in normal mice.

Hyuganatsu orange (Citrus tamurana Hort. Ex Tanaka) contains a water soluble substance that suppresses bone loss in ovariectomized rats.

We investigated whether Hyuganatsu orange (Citrus tamurana Hort. ex Tanaka) contains water and acetic-acid soluble substances that increase bone mineral density (BMD) in ovariectomized rats. In in vivo study, femoral BMD can significantly increased. In in vitro study, tartrate-resistant acid phosphatase (TRAP) positive cells significantly decreased. We speculate that Hyuganatsu orange contains biologically active substances other than hesperidin that increase BMD.

Effect of acute hepatic failure on the hepatic first-pass effect of 5-fluorouracil in rats.

OBJECTIVES: In cancer chemotherapy for hepatocellular carcinoma, 5-fluorouracil is widely used and has typically been given by intrahepatic arterial (i.a.) infusion to increase treatment efficacy and reduce systemic toxicity. 5-Fluorouracil is eliminated primarily by the liver and so the hepatic first-pass effect after intrahepatic arterial administration of 5-fluorouracil may be lower in patients with hepatic failure, and systemic toxicity may not be reduced. In this study, we have investigated the effect of acute hepatic failure on the first-pass effect of 5-fluorouracil in rats. METHODS: Experimental acute hepatic failure was induced by treatment with carbon tetrachloride (CCl4). 5-Fluorouracil was infused for 15 min into the hepatic artery or the saphenous vein of rats at a dose of 1.25 mg/kg. KEY FINDINGS: Hepatic availability in 50% CCl4-treated (severe hepatic failure) rats was higher than in controls. CONCLUSIONS: The hepatic first-pass effect after intrahepatic arterial administration of 5-fluorouracil was lower in severe hepatic failure. Therefore, the reducing effect of the systemic toxicity after intrahepatic arterial administration may be lower in severe hepatic failure.

Safety, efficacy and pharmacokinetics of S-1 in a hemodialysis patient with advanced gastric cancer.

PURPOSE: The safety and efficacy of S-1 in hemodialysis patients have not been established. We evaluated the safety and efficacy and pharmacokinetics of S-1 in a hemodialysis patient with advanced gastric cancer. PATIENT: A 66-year-old Japanese man with chronic renal failure, who had undergone hemodialysis three times a week for 3 years. Based on the diagnosis of stage IV gastric cancer, S-1 therapy was started. S-1 was administered 11 times at a daily dose of 23.5 mg/m(2) (40 mg/body)after hemodialysis, followed by a rest. One course was a period of 28 days. Blood samples were obtained after the first administration of S-1 and before beginning the fourth course. The concentration of 5-FU was determined by high-performance liquid chromatography. RESULTS: Area under the concentration-time curve (AUC)of 5-FU was 2647.2 ng h/mL after administration of S-1 of 23.5 mg/m(2) (40 mg/body). During the S-1 treatment,serious adverse events such as neutropenia were not observed; however, decreases in hemoglobin level were observed (grade 3). The treatment was well tolerated. After the second course of chemotherapy, the primary lesion showed a partial response and lymph node metastases and liver metastases showed stable disease. CONCLUSIONS: Our results suggest that S-1 is an important treatment option for patients with hemodialysis with advanced gastric cancer.

[Medical emergency education using emergency care simulators in the School of Pharmaceutical Sciences].

Clinical pharmacy training III (bedside training) in the School of Pharmaceutical Sciences, Kyushu University of Health and Welfare is intended to train pharmacists who can also cope with medical emergencies. Therefore we produced original scenarios that provide experience of various medical emergencies using emergency care simulators. As a result, these simulators enabled students to experience dealing with various medical emergencies such as cardiopulmonary resuscitation, automated external defibrillation (AED), adrenalin administration, and oxygen inhalation. In addition, a survey on the necessity for and the degree of the understanding of training contents associated with emergency care simulators was performed before and at the end of clinical training. After clinical training, the necessity for and the degree of the understanding of these training contents significantly increased (p<0.01). The introduction of emergency care simulators into clinical pharmacy training provides experience of not only cardiopulmonary resuscitation but also the treatment procedures as well as observation of improvement in the pathological condition after drug administration, which increases pharmacists' awareness of patient needs in drug therapy. Therefore these simulators are helpful for pharmacy education aiming at improving pharmacists' pharmaceutical care ability.

Analysis of CYP3A inhibitory components of star fruit (Averrhoa carambola L.) using liquid chromatography-mass spectrometry.

In this study, we analyzed the CYP3A inhibitory components of star fruit Averrhoa carambola L., using liquid chromatography-mass spectrometry (LC-MS). The stereoisomer of procyanidin B1 and B2 and/or the trimer consisting of catechin and/or epicatechin were suggested to be potent inhibitory components.

Effect of acute hepatic failure on epirubicin pharmacokinetics after intrahepatic arterial injection in rats.

In the case of cancer chemotherapy for hepatocellular carcinoma, anthracycline anticancer agents such as epirubicin are widely used, and have typically been given by intrahepatic arterial (i.a.) infusion to increase treatment efficacy and to reduce systemic toxicity. The anthracyclines are eliminated primarily by the liver, and the use of these drugs in patients with hepatic failure can be difficult. In this study, we investigated the effect of acute hepatic failure on the pharmacokinetics of epirubicin after i.a. injection in rats. Experimental acute hepatic failure was induced by carbon tetrachloride-treatment. Epirubicin was injected into the hepatic artery or the saphenous vein of the rats at a dose of 2 mg/kg. After both intravenous (i.v.) and i.a. injection, the serum concentration and the AUC 0-24 of epirubicin in hepatic failure rats were significantly higher than the values in control rats. The AUC 0-24 ratio of hepatic failure (i.a.) to control (i.a.) was higher than the ratio of hepatic failure (i.v.) to control (i.v.). These results suggest that the influence of hepatic failure on serum epirubicin concentration is larger with the i.a. route than with the i.v. route. The liver concentration of epirubicin after i.a. administration in hepatic failure rats was significantly lower than that in control rats. This result suggests that the effect of the liver-selective drug targeting after i.a. injection in hepatic failure rats is lower than in normal rats. Therefore, we should be careful when administering epirubicin by the i.a. route in patients with acute hepatic failure.

Inhibitory effects of fruit juices on cytochrome P450 2C9 activity in vitro.

There is limited information on the effect of fruits on human cytochrome P450 (CYP) 2C9 activity. The objective of this study was to determine the effect of fruit juice on CYP2C9-mediated drug metabolism. Nine citrus fruits and eight tropical fruits were chosen. We investigated effects of the fruits on diclofenac 4'-hydroxylation and tolbutamide hydroxylation by human liver microsomes. Among the fruits, pineapple juice showed potent inhibition of CYP2C9 activity. The addition of 25 microl (5.0% v/v) of pineapple juice resulted in almost complete inhibition. Next we examined the inhibitory effect of bromelain, a cysteine protease in pineapple. Bromelain also strongly inhibited CYP2C9 activity. In addition, E-64, a cysteine protease inhibitor, almost entirely blocked inhibition by pineapple juice and bromelain. Thus we found that pineapple juice was a potent inhibitor of CYP2C9, and that the inhibitory effect might be due to the bromelain contained in pineapple.

Inhibition of carrier-mediated uptake of epirubicin reduces cytotoxicity in primary culture of rat hepatocytes.

Epirubicin, an antineoplastic drug, is considered to be taken up by tumor cells via a common carrier by facilitated diffusion and is then pumped out in an energy-dependent manner because epirubicin is a substrate for P-glycoprotein (P-gp). However, this study investigated the details of the influx mechanism of epirubicin and demonstrated that epirubicin uptake was mediated by active carrier systems in addition to facilitated diffusion in the primary culture of rat hepatocytes. The uptake of epirubicin gradually increased in a saturated manner when the concentrations were between 1 x 10(-7) M and 1 x 10(-6) M. In contrast, the uptake increased progressively in a linear manner when the concentration was high (greater than 1 x 10(-6) M). The uptake of epirubicin at a clinical concentration (7.5 x 10(-7) M) was significantly reduced at 4 degrees C and significantly inhibited when pretreated with metabolic inhibitors (carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP), rotenone and sodium azide) by nearly 25%. Furthermore, an organic anion transporter inhibitor, namely, 4,4'-diisothiocyanato-stilbene-2,2'-disulfonic acid (DIDS); organic anion transport substrates, namely, para-aminohippurate (PAH), taurocholic acid and estradiol 17-beta-D-glucuronide; and organic cation transporter inhibitors, namely, verapamil and tetraethylammonium significantly reduced the uptake of epirubicin. Furthermore, pretreatment with verapamil and PAH significantly prevented epirubicin-induced reduction of proliferative activity in rat hepatocytes. These results indicated that the uptake of epirubicin was induced, at least in part, by the active transport protein in rat hepatocytes; the inhibition of the probable transport protein protected the intact normal cells from the injury induced by the cytotoxicity of epirubicin.

Adsorption of irinotecan onto oral adsorbent AST-120 (Kremezin) for preventing delayed diarrhea.

PURPOSE: One of the significant dose-limiting toxicities of irinotecan hydrochloride (CPT-11) is severe diarrhea due to impairment of the intestinal membrane induced by the excreted CPT-11 and its metabolites. AST-120 (Kremezin) is a prominent oral adsorbent that consists of porous spherical carbonic particles. To evaluate whether Kremezin can prevent the diarrhea induced by CPT-11, we investigated the adsorption characteristics of CPT-11 and its metabolites onto Kremezin in vitro and in vivo. METHODS: For in vitro studies, Kremezin was added to each solution containing one of the camptothecin drugs (CPT-11, SN-38, and SN-38-glucuronide), and adsorption activities were determined under various conditions. For in vivo studies, CPT-11 was consecutively administered, and the occurrence of diarrhea was compared between Kremezin-treated and non-treated rats. RESULTS: Kremezin drastically adsorbed the camptothecin drugs in vitro, and the adsorption percentages of the camptothecin drugs for 60 min were more than 85%. In addition, the frequency of diarrhea in Kremezin-treated rats decreased by approximately half of that in the non-treated rats. CONCLUSION: Kremezin showed potent adsorption capacities for the camptothecin drugs and mitigated the symptoms of diarrhea in rats. These results suggest that Kremezin is useful to prevent the diarrhea in clinical CPT-11 chemotherapy.

Effects of pomegranate juice on human cytochrome P450 2C9 and tolbutamide pharmacokinetics in rats.

In this study, we investigated whether pomegranate juice could inhibit CYP2C9 activity. The ability of pomegranate juice to inhibit the diclofenac 4'-hydroxylase activity of human CYP2C9 was examined using human liver microsomes. Pomegranate juice was shown to be a potent inhibitor of human CYP2C9. The addition of 25 microl (5% v/v) of pomegranate juice resulted in almost complete inhibition of human CYP2C9 activity. In addition, we investigated the effect of pomegranate juice on the pharmacokinetics of tolbutamide (substrate for CYP2C9) in rats. Relative to the control group, the area under the concentration-time curve was approximately 1.2-fold greater when pomegranate juice (3 ml) was injected p.o. 1 h before the p.o. administration of the tolbutamide (20 mg/kg). The elimination half-life of tolbutamide was not altered by pomegranate juice administration. These results suggest pomegranate juice ingestion inhibits the intestinal metabolism of tolbutamide without inhibiting the hepatic metabolism in rats. Thus, we discovered that pomegranate juice inhibited human CYP2C9 activity and furthermore increased tolbutamide bioavailability in rats.

Transient inhibition of cyp3a in rats by star fruit juice.

Star fruit juice is a potent in vitro inhibitor of CYP3A; however, few reports are available on the inhibition of CYP3A activities by star fruit juice in vivo. Therefore, in this study, we investigated the CYP3A-mediated star fruit-drug interaction in vivo. The effect of star fruit juice on carbamazepine pharmacokinetics was examined in rats. In comparison with water, the area under the concentration-time curve (AUC) of carbamazepine was approximately 1.3-fold greater when star fruit juice (2 ml) was orally administered 1 h before the oral administration of carbamazepine (50 mg/kg). In contrast, the elimination half-life of carbamazepine and the AUC ratio of carbamazepine 10,11-epoxide to carbamazepine were not altered by the administration of star fruit juice. These results suggest that star fruit juice impairs the function of enteric CYP3A, but not of hepatic CYP3A. In addition, we evaluated the time course of recovery of CYP3A activity that was reduced after the treatment with star fruit juice. The inhibition by star fruit juice was recovered within approximately 24 h. These data suggest that the effect of star fruit juice is mainly reversible and transient. Thus, we discovered that star fruit juice alters the carbamazepine pharmacokinetics in rats.

Isolation of cytochrome P450 3A (CYP3A) inhibitors from Hyuganatsu, Citrus tamurana Hort.

The present study was conducted to identify cytochrome P450 3A (CYP3A) inhibitory components of Hyuganatsu, Citrus tamurana Hort., by investigating the effects on midazolam 1'-hydroxylase activity of human liver microsomes. As a consequence, limonin and nomilin were identified as CYP3A inhibitors from the endocarp of Hyuganatsu.

Inhibitory effects of amino-acid fluids on drug binding to site II of human serum albumin in vitro.

The effects of amino-acid fluids on ligand binding to human serum albumin (HSA) were investigated by fluorescence and ultrafiltration techniques. Warfarin and dansylsarcosine were used as the site marker fluorescence probes for site I and site II of HSA, respectively. Amino-acid fluids specifically decreased the fluorescence intensity induced by dansylsarcosine-HSA binding without any effects on that induced by warfarin-HSA binding. The ultrafiltration technique clarified that the free fraction of the site II drug, diazepam, in human serum was increased in the presence of amino-acid fluids, while no effect was observed in the free fraction of the site I drug, warfarin. The potencies of the effect on binding to site II, observed by fluorescence and ultrafiltration techniques, correlated well with the L-tryptophan contents in amino-acid fluids or with those in L-tryptophan solutions. Based on the comparison between the effects of amino-acid fluids and L-tryptophan solutions, we confirmed that L-tryptophan in amino-acid fluids specifically inhibits drug binding to site II of HSA.

Effects of pomegranate juice on human cytochrome p450 3A (CYP3A) and carbamazepine pharmacokinetics in rats.

In this study, we investigated whether components of pomegranate could inhibit CYP3A-mediated drug metabolism. The ability of pomegranate to inhibit the carbamazepine 10,11-epoxidase activity of CYP3A was examined using human liver microsomes, and pomegranate juice was shown to be a potent inhibitor of human CYP3A. Addition of 25 microl (5.0% v/v) of pomegranate juice resulted in almost complete inhibition of the carbamazepine 10,11-epoxidase activity of human CYP3A (1.8%). The inhibition potency of pomegranate juice was similar to that of grapefruit juice. In addition, we investigated the in vivo interaction between pomegranate juice and carbamazepine pharmacokinetics using rats. In comparison with water, the area under the concentration-time curve (AUC) of carbamazepine was approximately 1.5-fold higher when pomegranate juice (2 ml) was orally injected 1 h before the oral administration of the carbamazepine (50 mg/kg). On the other hand, the elimination half-life of carbamazepine and the AUC ratio of carbamazepine 10,11-epoxide to carbamazepine were not altered by the injection of pomegranate juice. These data suggest that pomegranate juice component(s) impairs the function of enteric but not hepatic CYP3A. Thus, we discovered that a component(s) of pomegranate inhibits the human CYP3A-mediated metabolism of carbamazepine. Furthermore, pomegranate juice alters the carbamazepine pharmacokinetics in rats.